JPS6028843B2 - Method for producing polytetramethylene adipamide prepolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves heating 1,4-diaminobutane and adipic acid salt under high pressure to produce a prepolymer, and condensing this prepolymer to obtain polytetramethylene azide having a sufficiently large molecular weight. The present invention relates to a method for producing a polytetramethylene adipamide prepolymer when obtaining a polytetramethylene adipamide.

The object of the present invention is to carry out aftercondensation.
The object of the present invention is to provide a method for forming a prepolymer which can be converted into a high molecular weight white polyamide in a liquid phase in a short period of time.

According to the invention, after heating the salt of 1,4-diaminobutane and adipic acid, if necessary together with a polyamide-forming compound selected from lactams and aminocarboxylic acids to form a prepolymer, the next step fNH-(CH2)4 by converting this prepolymer into polytetramethylene adipamide by post-condensation at high temperature at
While it is possible to make polyamides consisting essentially of units of -NH-C○(CH2)4-CO, in the process of the invention the prepolymerization is carried out in an excess of 0.5 to 15 mol%. - heating the salt in the presence of 4-diaminobutane to a temperature of 150 to 310 oo at a steam partial pressure of less than 30 bar and maintaining the reaction mixture in liquid form at a temperature of 150 to 310 oo for a certain time in the final stage of prepolymerization; , the water vapor partial pressure not exceeding 30 bar and the reaction product being liquid during the entire polymerization, the amount of cyclic end groups being 9 equivalents of 0.20 per prepolymer. This is done by stopping the prepolymerization before the temperature is exceeded.

．． Using this method, a white prepolymer can be produced without any problems which can be converted into a high molecular weight white polyamide by subsequent condensation. According to the knowledge of the present applicant, prepolymerization of 1,4-diaminobutane and adipic acid is sensitive to side reactions.

Presumably, if the reaction is carried out under conditions that are not carefully controlled, cyclic derivatives of 1,4-diaminobutane, cyclized oligomers and prepolymers with cyclic end groups are formed. Important for the proper progress of the reaction are the reaction temperature, the temperature if the reaction products are maintained for a limited period of time, the total reaction time and the water vapor partial pressure during the reaction.

It is also desirable to avoid local overheating of the reactants.
This is especially true when the reaction products must be kept in the solid state for some time. Therefore, the reaction product is 1
50 to 31000 at a maximum heating rate of 3.5 qo/
It is advantageous to limit it to minutes. Higher heating rates may cause discoloration of the prepolymer, making subsequent conversion of the high molecular weight polyamide by condensation difficult.

From a practical standpoint, a heating rate of at least 0.1° C./min is often applied. A heating rate suitable in all cases is between 0.5 oo/min and 2°C/min. There is little restriction on the rate at which the reaction products are heated to 150oC. Raising the temperature to 75-100 oo can be done in a very short time. The salt of 1,4-diaminobutane and adipic acid can be added as a wet dry solid or as an aqueous solution or slurry.

Preferably, the amount of water fed is at most 5% by weight, calculated on the amount of polyamide-forming compound and water. If a significant amount of water is used, the water vapor partial pressure can be kept below the upper limit of 30 bar by blowing off the steam. In connection with the post-condensation, it is preferred to apply an excess of 1,4-diaminobutane, as detailed in the co-filed patent specification. The reaction mixture is 15
Heat to a temperature of 0-31000.

At temperatures below 150 qo, the molecular weight of the prepolymer becomes too small.

At temperatures above 3,100 degrees, the prepolymer will undergo severe discoloration and subsequent condensation will become very difficult.

Therefore, a temperature of 175 to 300 oo is optimal for producing a white prepolymer having a sufficiently large molecular weight and which can be reliably post-condensed. Particularly optimal temperature is 175-22
It is 000. The reaction mixture can be heated to the desired temperature in a single step, but it can also be heated in two or more steps, in which case the mixture can be held at a temperature between 175 and 30,000 °C for short or long periods of time. The total prepolymerization time including heating time is generally 1. It is between the vowels and the 6th hour. When the reaction is carried out at temperatures above 220°C, it has been found to be advantageous to keep the reaction time at 220°-31000°C to the minimum time necessary to heat the reaction products to the required temperature.

Temperature range is 150-2000C, preferably 175-20C
If it is zero, the reaction product can be held at a constant temperature for a longer period of time, for example 15 to 120 minutes.

Whether the reaction products are in the solid or liquid state depends on the temperature, degree of polymerization, and water content of the reaction products, this last factor being related to the water vapor partial pressure of the reactor.

At any stage of prepolymerization, the reaction product may be present in a completely solid state or in the form of a slurry containing solid particles. In order to recover the prepolymer from the reactor, the reaction product is preferably in liquid form at the end of the reaction, ie at least before removal from the reactor. However, in order to obtain a high degree of polymerization, to obtain a uniform product, and to avoid discoloration due to localized overheating, it is preferable to maintain the reaction product in liquid form throughout the prepolymerization process. This objective can be achieved by choosing a high water vapor partial pressure (PH number) such that a sufficient amount of water remains in the reaction product to keep it liquid at the condensation temperature. A sufficient amount of water is produced during the condensation reaction, but if desired it is also possible to feed water to the reactor in addition to the salt. For this purpose, depending on the degree of polymerization, it is generally sufficient to apply a PH momme of about 20 to 2> at a temperature of 150 to 300 oo. However, a PH2 of about 30 bar at the prepolymerization temperature. Exceeding should be avoided. If PH2o is above 30 bar, prepolymers are obtained which are difficult to convert into high molecular weight polyamides by post-condensation. PH2.

is preferably higher than the minimum partial pressure necessary to keep the reaction products in liquid form and less than 5 bar. Since the prepolymer has a melting point between 270oC and 290oC, a liquid prepolymer containing almost no water can be prepared by heating the reaction product above the melting point and releasing the pressure at a final temperature around that point. can be obtained.

Therefore, adjust the PH2o and adjust the temperature to e.g.
Heat the salt while increasing continuously from 0 to 30,000 degrees Celsius or preferably to a temperature in the range of 180 to 200 degrees, maintain the temperature in this range for a limited time, then increase the temperature to e.g. Prepolymerization can be carried out by raising the temperature to ~300o0. On the other hand, it is also possible to stop the prepolymerization at temperatures below 270 pm by removing the liquid reaction product from the reactor and bringing the pressure to atmospheric. In this case, water comes out of the reaction product, so that a solid state prepolymer is obtained. According to the applicant's knowledge, it is extremely important to keep the number of cyclic end groups in the prepolymer as small as possible.

These terminal groups are essentially pyrrolidinyl groups. When more than 0.20 equivalents/ta of cyclic end groups are present, it becomes very difficult to convert the prepolymer into a high molecular weight polyamide in a reasonable amount of time. The content of cyclic end groups is 0.
9 equivalents/unit from 10 to 0.20, preferably from 0.10 to 0
．． The 15 mg/eq. Can be converted into prepolymers. The reaction is preferably carried out under conditions such that the content of cyclic end groups in the prepolymer is at most 0.10, 9 equivalents/equivalent. This is because in this case, the prepolymer can be easily converted into a high molecular weight polymer. For example, the salt can be made by known methods, such as by adding adipic acid to a solution of 1,4-diaminoptan until the equivalence point is reached.

If desired, excess diamine can be added to the salt. As explained in Hakama Sekisho 56-149431 submitted at the same time, 0.5 to 15 mol%, more preferably 1
．． Applying an excess of diamine of 5 to 5 mol % provides various advantages. Excess amounts of diamine do not adversely affect prepolymerization. The salts can be fed to the prepolymerization reactor in dry or wet form, or as an aqueous solution or an aqueous slurry. Reactors that can be used are autoclaves or pressure reactors, which may or may not have casing means. The reaction can also be carried out continuously in a reactor suitable for this purpose. To avoid discoloration, it is desirable to carry out the prepolymerization in the absence of oxygen and to construct the reactor from a material such as titanium that is resistant to corrosion by hot alkaline reactants. After the reaction, the prepolymer is subjected to post-condensation.

The reaction is preferably carried out in the solid phase in an atmosphere containing water vapor at a temperature of 220 to 275 oo, preferably 225 to 275 oo. The post-condensation was submitted at the same time as JP-A-56-11.
49431, so please take a look. It is possible to add to the reaction mixture for prepolymerization additives commonly used in polyamides, such as stabilizers, antioxidants, matting agents, etc. Besides diaminobutane and adipic acid, up to 2% by weight of other polyamide-forming compounds can also be added to the prepolymer.

Incidentally, such compounds may include caprolactam, undecalactam, laurirolactam and other lactams, as well as aminocarboxylic acids such as 11-aminoundecacarboxylic acid. However, it is preferred to produce homopolyamides with very good physical properties. The number average molecular weight of the prepolymer obtained by applying the method of the present invention may generally be from 1,000 to 15,000.

Preferably, the reaction conditions, especially temperature, moisture content and reaction time, are selected in such a way that a prepolymer having a molecular weight of 2,000 to 10,000 can be obtained. The molecular weight is reduced to 15 by post-condensation.
000 to 75,000 polyamides can be obtained.
This polyamide is highly suitable for obtaining various products such as threads. The present invention will now be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A A salt of 1,4-diaminobutane and adipic acid was prepared as follows.

Dissolving 1 part by weight of the above diamine in 8 parts by weight of methanol,
The resulting solution was then charged into a reactor equipped with a stirrer and a reflux condenser. Then, while stirring, solid adipic acid was slowly added until the equivalence point was reached. After cooling,
The precipitated salt was filtered off, washed with low-temperature methanol, and then dried. 1,4-diaminobutane was added in an excess of 2.1 mol%.

Unless otherwise specified, salts were made in the same manner in the following examples. B 1,700 ml of the salt obtained in A and 170 ml of water were charged into the autoclave.

After flushing with nitrogen, these were heated to 180 °C for 80 minutes.
℃ and held at this temperature for 100 minutes. During this time the pressure rose to 8 bar and this pressure was maintained. After this, the pressure was lowered to 1 bar and the reaction product was cooled. A solid white prepolymer was discharged from the reactor. The relative viscosity of this is 1.33 (2000, 96% sulfuric acid 100%
Polymer 1) with a cyclic end content of [phr] 0
．． 0.032 female equivalents/1 polymer. In the following examples, the same method was applied for prepolymerization, except that the temperature, time and pressure were varied.

The same results were obtained using salts containing diaminobutane until the equivalence point was reached. C prepolymer at about 0.
After grinding to a particle size of 1 to 0.2 grains, it was charged into a rotary reactor suitable for carrying out the reaction. An oxygen-free gas mixture consisting of 3% by volume of steam and 70% by volume of nitrogen, heated to 260 oo, was passed through the rotary reactor at a pressure of 1 bar. The prepolymer was postcondensed in this manner at a temperature of 260°C for 6 hours. In this case, the above mixed gas was sent. This method was also applied to the post-condensation in the following examples.

In this way, 9 equivalents of white polytetramethylene adipamide having a rel of 4.65 and a [pyr] of 0.005 was obtained.

Example 0 A prepolymer was prepared according to the method of Example 1 by heating a salt containing an 8 mol % excess of diaminobutane from 7yo to 155°C for 55 minutes and then from 155qo to 20,000 for 16 minutes. made.

The maximum pressure was 1 or less gallons. The resulting prepolymer was white and had a Rel of 1.23, a Mn of 3500, and a [p] of 0.028, 9 equivalents/unit. Post-condensation (6 hours at 260qC) resulted in a rel of 4.9
0 (corresponding to 34700Mn), a white polymer polyamide could be obtained. Example m A mixture of 15 parts by weight of water and 10 parts by weight of the salt of 114-diaminobutanoadipic acid containing an excess of 5.4 mol % diamine is heated from 75q0 to 17500 in 75 minutes and then heated to 100 Heated to 2070 degrees in minutes.

The pressure was limited to 10 bar by blow-off. The Mn of the obtained prepolymer was 4500, and [pyh]
is 0.122 skin equivalent/unit. Post-condensation (6 hours at 260 oo) reduced this prepolymer to a rel of 3.3.
7 (corresponding to Mn 27400) was converted into white polyamide. Example W 1 containing 15 parts by weight of water and an excess of 8 mol% diamine
- A mixture with 10 parts by weight of the salt of 4-diaminobutanoadipic acid was heated from 20°C to 210q0 in 240 minutes.

The pressure rose to 19 bar. Post-condensation (6 at 26000
The prepolymer was converted into a white polyamide with an Mn of 24,800. Example V A methanol solution of adipic acid is added to a methanol solution of 1,4-diaminobutane until the equivalence point is reached.
A salt of 4-diaminobutanoadipic acid was obtained.

The reaction mixture was cooled and the salts were collected by filtration, washed with methanol and dried. 1. converted to dry salt. Round weight percent of the above diamine was added. Salt was charged to the autoclave.

After flushing, the autoclave was heated. A temperature of 215 qo was reached in 220 minutes (average heating rate of 0.8 C/min, actual heating rate was 0.1500/min and 2.yC/min).
(changed between minutes).

During this time the pressure rose from 1 bar to 14.6 bar. After this the pressure was lowered to 1 bar by blow-off and the reaction product was cooled. As a result, a solid white prepolymer with Mn of 3500 was obtained. 1,4-diaminobutane was prepared by the method described in Example V of the Examples.
．． A 3% weight excess of salt was made.

Charge salt into the autoclave, and add salt to an average of 0.800
Prepolymerization was carried out by heating to 23,300°C for 245 minutes at a heating rate of 245 minutes.

During this time the pressure rose to 18.7 bar. The prepolymerization was interrupted by reducing the pressure to 1 bar and cooling the reaction product. As a result, a white prepolymer having Mn of 4100 was obtained. EXAMPLE A mixture of 1,700 g of the salt of 1,4-diaminobutanoadipic acid containing an excess of 2.4 mol% of 1,4-diaminobutane and 170 g of water was heated to 180 g for 60 minutes, and then Heated from 18,000 to 29,500 in 50 minutes.

In the temperature range from 20,000 to 26,000 degrees, the pressure is limited to 13 g by ventilation, and from 260 o'clock to 29 o'clock
The pressure was gradually released in the range of 500 to 1 bar at 29,500.

The molten prepolymer was removed from the reactor, cooled, and ground. The white prepolymer glue rel is 1.66,
[pyr] was 0.64 kite 9 equivalents/night. This was subjected to solid phase post-condensation (at 2600C for 4 hours) until the rel was 2.
．． 65 polyamide was converted. Example Skin The method of Example Skin was repeated using the same starting composition, but the temperature was increased to 180 qo in 60 minutes.

This temperature was then maintained at a pressure of 8 bar for 60 minutes, and then the reaction product was heated to 295 qo in 4 minutes. The obtained prepolymer paste rel was 1.66, [pM]
was 0.053 9 equivalents/unit. It was possible to convert this into a polyamide with a rel of 2.75. EXAMPLE K The same starting mixture used in Example Skin was heated to 22 kg in 78 minutes.
Heat to 0qo, hold at this temperature for 20 minutes and reduce pressure to 18
．． I raised the veil.

The reaction product was then heated to 295 qo for 30 minutes, while the pressure was gradually released from 26,000 qo. prepolymer
The glue rel was 1.63, and the [pM] was 0.078 female equivalent/unit. (Do the same with 260 circles for 4 hours)
By post-condensation, a polyamide with a rel of 2.65 was obtained. Example X The method of Example K was followed, but the reaction product was
It was held for 20 minutes and the pressure was increased to 22.5 bar.

The prepolymer has a rel of 1.49 and a pM of 0.
It was 9 equivalents of 192/night. Post-condensation beam rel is 1.
81 polyamide was obtained. From the above results, it can be seen that it is not desirable to maintain the temperature at 20,000 or higher for too long. This is because as [p〆] increases, the molecular weight of the target substance decreases. Example
The method of Example K was followed, but the temperature was raised to 250°C in 8 minutes.

This temperature was maintained for 20 minutes and the pressure was increased to 27 bar. The temperature was then increased to 295 qo in 20 minutes. The prepolymer had a rel of 1.49 and a p of 0.173. Post-condensation beam rel is 1.90
of polyamide. EXAMPLE The method of the mowing example was repeated, but this time the molten prepolymer was held at 29500, 1 bar (steam) for a total of 60 minutes.

The obtained prepolymer paste rel was 1.73, [py
r] was 0.072 double 9 equivalents/unit. Post-condensation beam r
A faded polyamide with an e1 of 2.38 was obtained. EXAMPLE The method of Fox Example Skin was repeated, but this time using a mixture of 1000 g of salt and 300 g of water. rel is i. At 64,
A prepolymer of 9 equivalents/unit with a [pM] of 0.074 was obtained which (in 260q04 hours) had a rel of 2.5.
0 polyamide was successfully converted. Example
8000 and maintained at this temperature for an additional 6 flours.

The pressure was maintained at a maximum of 6 bar. The reaction product was then heated to 29,500 degrees Celsius for 35 minutes to a maximum pressure of 13 degrees. During this time, the pressure was gradually released from 260q○.
The obtained prepolymer paste rel was 1.65, [py
r] was 0.068 9 equivalents/unit. Postcondensation (26
4 hours at 0qo) to give a polyamide with a beam rel of 2.47. Example XV (not according to the invention - comparative example) A method suitable for manufacturing nylon 6.
The starting material was a mixture of 1000 g of diaminobutane/salt of adipic acid (2.4 mole % excess of diamine) and 700 g of water.

The mixture was then heated to 21500°C in 60 minutes and then raised from this temperature to 275°C in 120 minutes. The pressure was maintained at a maximum of 1> After this, the reaction product was
The mixture was heated to 295 oo in minutes and the pressure was gradually released. sword r
A white prepolymer with an el of 1.36 and a [pM] of 0.263 was obtained, weighing 9 equivalents/equivalent. Post-condensation (4 hours at 26,000) was performed using a sword rell. 71 polyamide was obtained. It is clear that this method is not suitable for the production of nylon 4.6. Example XW The method of Example XV was repeated.

However, the temperature was increased from 215 degrees 0 to 27500 degrees every 3 seconds. The prepolymer beam rel of this example is 1.5
0, [pyr] was 0.143 mg equivalent/night.
Post-condensation increased the rel to 1.88. Example
A mixture of 10 parts by weight of X-hada diaminoptan/salt of adipic acid (2.0 mol% excess of diamine), 10 parts by weight of caprolactam and 10 parts by weight of water was heated to 18-0 for 60 minutes, and at this temperature 18 parts of powder was added. I maintained it for a while.

During this time the pressure was up to 8 bar. After this, a prepolymer was obtained in the same manner as in Example 1. This sword rel is i
．． 18, [pyr] was 0.046 9 equivalents/night. Post-condensation (4 hours at 260 x 0) beam rel is 3.2
No. 5 nylon 6.46 copolymer was provided. Example
X-Leg Example X The blood procedure was repeated, but this time using 1 part by weight of 11-aminoundecanoic acid.

The prepolymer glue rel is 1.20 and [p] is 0.
The amount was 9 equivalents of 0.030/night. Post-condensation (4 at 26000
Time) gave nylon 11.46 with a sword rel of 2.51. This example was repeated using 2 parts by weight of 11-aminoundecanoic acid, but the resulting prepolymer paste r
el is 1.18, [pyr] is 0.035 9 equivalents/
It was evening.

Post-condensation (6 hours at 25000) gave a copolyamide with a rel of 2.42. EXAMPLE X A number of prepolymers were made using a salt of 114-diaminobutane and adipic acid (1.1 mol% excess of diaminobutane) and varying the amount of water.

In each case, the mixture was heated to the desired temperature for about 2 hours and maintained at this temperature for 5 minutes before the reaction products were removed from the reactor and allowed to cool while releasing the pressure. The prepolymer was then post-condensed in the manner of Example 1 at 260 CO for 4 hours. The moisture content, maximum temperature, maximum pressure of the starting mixture, and physical property data of the prepolymer and final product are summarized in Table 1.

Table 1 *By introducing political righteousness, pressure was exerted on Tokoro Tsubok.

Determination of pyrrolidine end groups in nylon 4.6 A glass tube containing 0.25 mm of dry polyamide and 0.5 mm of isohydrochloric acid was flushed with nitrogen, then sealed and heated to 130° C. in an oil bath. Maintain this temperature until the polyamide melts,
It was maintained for an additional 4 hours. Next, when the glass tube is cooled,
Crystals of adipic acid precipitated. I opened it after this. A sample for gas chromatography-analysis was prepared by diluting 0.20% of the liquid floating on the surface with 0.70% of 2N alcoholic sodium hydroxide. The analysis is 150qo
220°C at a heating rate of 1300/min.
1.5 x 1/4" preconditioned by heating to
Chromosorb-(RTM) 1
The sample was run using 30 columns and 1 sample. Detection was performed by flame ionization method. A pyrrolidone peak was detected after 4.5 minutes, and a 1,4-diaminobutane peak was detected after 8 minutes.

Claims (1)

Claims: 1. A polyamide-forming compound selected from a salt of 1,4-diaminobutane and adipic acid, and optionally a lactam and an aminocarboxylic acid, is heated to form a prepolymer, which is then condensed. By making it into a high molecular weight polyamide, -[NH-(CH_2)_4-NH-CO
-(CH_2)_4-CO]- When producing the above prepolymer to obtain polytetramethylene adipamide consisting essentially of units of -(CH_2)_4-CO]-, prepolymerization is
．． 150 °C and 31 °C at a water vapor partial pressure of up to 30 bar in the presence of an excess of 1,4-diaminobutane of 5 to 15 mol%.
Heating the above salt in liquid form to a temperature between 0°C and maintaining the reaction mixture in liquid form for a limited time at a temperature between 150°C and 310°C in the final stage of prepolymerization; the water vapor partial pressure does not exceed 30 bar and the reaction product is liquid during the entire polymerization,
A method for producing a polytetramethylene adipamide prepolymer, characterized in that prepolymerization is stopped before the amount of cyclic terminal groups exceeds 0.20 mg equivalent per gram of prepolymer. 2. The method according to claim 1, wherein the reaction temperature is between 175°C and 300°C. 3 The content of cyclic end groups in the prepolymer is 0.1 mg
The method according to claim 1 or 2, in which the amount does not exceed the equivalent weight/g. 4. Process according to any one of claims 1 to 3, characterized in that the reaction time is kept to a minimum in the temperature range from 220 to 300°C. 5. Any one of claims 1 to 4 that does not increase the steam partial pressure by more than 5 bar above the minimum partial pressure necessary to maintain the reaction product in a molten state at a given temperature and degree of polymerization. The method described in section. 6. A method according to any one of claims 1 to 5, wherein the temperature is between 175°C and 220°C. 7. Claims 1 to 6 using as starting material a mixture of a salt of 1,4-diaminobutane/adipic acid and up to 50% by weight of water, based on the amount of salt and water.
The method described in any one of the preceding paragraphs. 8. A method according to any one of claims 1 to 7 for producing a prepolymer having a number average molecular weight between 1,000 and 15,000. 9. A method according to any one of claims 1 to 8 for producing a prepolymer having a number average molecular weight between 2,000 and 10,000. 10. Process according to any one of claims 1 to 9, characterized in that an excess of 1,4-diaminobutane of from 1.5 to 5 mol % is used.